共查询到20条相似文献,搜索用时 15 毫秒
1.
化学-酶级联催化结合了化学催化的广泛反应性与生物催化的高选择性,是不对称合成高附加值手性化合物的有效途径。然而,化学催化剂和酶之间以及它们反应条件之间的不相容性极大地限制了这一领域的发展。因此设计可行的方法解决这些问题,实现两种催化范畴的兼容和优势互补,将使化学-酶级联催化反应得到更广泛的应用。综述了近年来克服化学催化与酶催化不相容性所采取的一些策略以及相关的研究进展,如时间分隔、空间分隔和集成催化剂等,并介绍了化学-酶级联催化在手性化合物动态动力学拆分及手性药物合成方面的应用,最后展望了该领域未来的局限性和发展趋势。 相似文献
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生物催化在糖苷合成中的应用 总被引:1,自引:0,他引:1
较详细地综述了目前国外生物催化合成糖苷的研究进展,并对生物催化制备糖苷的酶的种类、反应介质、反应机理、反应类型及其影响因素进行了介绍。比较了各种生物催化合成糖苷的方法:糖苷酶催化合成糖苷产率一般较低;糖基转移酶需要以昂贵的活化的核苷糖作为糖基供体在辅酶的参与下合成糖苷;用糖苷合成酶合成寡糖,不仅具有立体选择性和区域选择性,而且效率高、底物便宜;全细胞催化合成糖苷具有产率较高,环境友好,产物纯度高且易分离等优点。认为全细胞催化是糖苷合成的重要方法,具有重要的应用价值,该方法值得深入研究。 相似文献
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Roland Wohlgemuth 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(12):1055-1062
The path to new chemical entities often shows the limitations of existing tools both in biocatalysis and organic chemistry. Organic synthetic procedures to prepare a compound in a target‐oriented synthesis can damage other functional parts of the molecule. Protection–deprotection schemes can lead to a dead end, when a certain protecting group cannot be cleaved off. In biocatalysis, on the other hand, the required biocatalytic toolbox and methodology might not be readily available, therefore limiting a biocatalytic approach. New toolboxes, ingredients, and methodologies at the interface of classical organic synthesis and biocatalytic reactions bridge the gap between these two areas. Since product isolation and purification involves a substantial amount of time in the preparation of chemicals, methodologies to simplify these tasks are necessary to get the pure product into the bottle with less work‐up time. Efficient and safe new pharmaceuticals, intermediates and analytical reagents need to be prepared under certain safety, health, environmental and economical boundary conditions. Biocatalytic reactions have been shown to overcome these limitations successfully and are becoming increasingly important in industrial manufacturing. Building bridges between biocatalysis and organic synthesis will therefore create roads to new synthetic strategies and technological frontiers of both fundamental and practical interest. Copyright © 2007 Society of Chemical Industry 相似文献
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Holger Wack Anke Nellesen Kerstin Schwarze‐Benning Görge Deerberg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(4):519-524
BACKGROUND: This paper focuses on the development of temperature induced phase transition hydrogels based on poly(N‐isopropylocrylamide (PNIPA) copolymers and their application as an immobilization matrix for biocatalysts. RESULTS: PNIPA‐co‐AAc and PNIPA‐co‐MAAc hydrogels were synthesized with different comonomer concentrations and analysed. In order to evaluate the capacity of hydrogels to take up or to release liquids the mass exchange capacity is introduced. In the presented work mass exchange capacities up to 22.4 were realized. To enhance the mechanical stability, composites of hydrogels and cellulosic fleeces were prepared. The enzyme Lipozyme ® TL 100 L (Thermomyces languniosa Lipase) was successfully inserted into the hydrogels and into the hydrogel composites. Lipase‐catalysed transesterification of rapeseed oil with ethanol to the corresponding ethyl ester was investigated to prove the activity of immobilized enzyme and thus, the concept. The activity was found to be similar to that of free enzyme. CONCLUSION: Smart hydrogel composites were used for the transesterification of oil. Based on the results obtained, reversible loadable and mechanical stable hydrogel composites could be developed for continuous working reactor concepts. Copyright © 2010 Society of Chemical Industry 相似文献
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金属有机框架(MOFs)具有比表面积大、设计性强和生物相容性好等优良特性,可以作为固定化酶的理想载体,从而提高游离酶的稳定性和催化性能,许多酶/MOFs复合材料也显示出比游离酶更好的催化性能。因此,酶/MOFs复合材料已应用于生物传感、检测、催化等领域,已成为传统催化剂的环保替代品。综述了酶在MOFs上的3种固定化方法(表面固定、孔封装和原位包埋法),重点介绍了4种影响酶/MOFs复合材料催化性能的因素及调控方法,对酶/MOFs复合材料在催化方面的应用也进行了总结,并对酶固定化的未来进行了展望。 相似文献
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Gold nanoparticles supported on metal oxides and activated carbon are able to catalyze the benzannulation reaction of o-(phenylethynyl)benzaldehyde and phenylacetylene to 1-benzoyl-2-phenylnaphtalene with high selectivity at 99% conversion.
Benzannulation of ortho-alkynyl benzaldehydes is a reaction typically catalyzed by soluble AuCl3 and, now, we have found that it can also be catalyzed by heterogeneous gold supported catalysts. The heterogeneous catalytic
system can be reused several times without loss of activity or selectivities. 相似文献
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Bridging the gap between research and standards 总被引:1,自引:0,他引:1
R.D. Hooton 《Cement and Concrete Research》2008,38(2):247-258
9.
Fatma Feyza Özgen Michael E. Runda Assist. Prof. Sandy Schmidt 《Chembiochem : a European journal of chemical biology》2021,22(5):790-806
In the field of green chemistry, light – an attractive natural agent – has received particular attention for driving biocatalytic reactions. Moreover, the implementation of light to drive (chemo)enzymatic cascade reactions opens up a golden window of opportunities. However, there are limitations to many current examples, mostly associated with incompatibility between the enzyme and the photocatalyst. Additionally, the formation of reactive radicals upon illumination and the loss of catalytic activities in the presence of required additives are common observations. As outlined in this review, the main question is how to overcome current challenges to the exploitation of light to drive (chemo)enzymatic transformations. First, we highlight general concepts in photo-biocatalysis, then give various examples of photo-chemoenzymatic (PCE) cascades, further summarize current synthetic examples of PCE cascades and discuss strategies to address the limitations. 相似文献
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Guillermo Cruz Laura Pilar Saiz Muhammad Bilal Lobna Eltoukhy Christoph Loderer Jesús Fernndez-Lucas 《International journal of molecular sciences》2022,23(21)
Enzyme-mediated processes have proven to be a valuable and sustainable alternative to traditional chemical methods. In this regard, the use of multi-enzymatic systems enables the realization of complex synthetic schemes, while also introducing a number of additional advantages, including the conversion of reversible reactions into irreversible processes, the partial or complete elimination of product inhibition problems, and the minimization of undesirable by-products. In addition, the immobilization of biocatalysts on magnetic supports allows for easy reusability and streamlines the downstream process. Herein we have developed a cascade system for cladribine synthesis based on the sequential action of two magnetic biocatalysts. For that purpose, purine 2′-deoxyribosyltransferase from Leishmania mexicana (LmPDT) and Escherichia coli hypoxanthine phosphoribosyltransferase (EcHPRT) were immobilized onto Ni2+-prechelated magnetic microspheres (MagReSyn®NTA). Among the resulting derivatives, MLmPDT3 (activity: 11,935 IU/gsupport, 63% retained activity, operational conditions: 40 °C and pH 5–7) and MEcHPRT3 (12,840 IU/gsupport, 45% retained activity, operational conditions: pH 5–8 and 40–60 °C) emerge as optimal catalysts for further synthetic application. Moreover, the MLmPDT3/MEcHPRT3 system was biochemically characterized and successfully applied to the one-pot synthesis of cladribine under various conditions. This methodology not only displayed a 1.67-fold improvement in cladribine synthesis (compared to MLmPDT3), but it also implied a practically complete transformation of the undesired by-product into a high-added-value product (90% conversion of Hyp into IMP). Finally, MLmPDT3/MEcHPRT3 was reused for 16 cycles, which displayed a 75% retained activity. 相似文献
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近年来,固载化L-脯氨酸及其衍生物手性催化剂因其具有均相催化剂的高活性和高选择性以及非均相催化剂的高循环使用性,被广泛用于催化不对称有机化学反应。本文简单介绍了L-脯氨酸及其衍生物的种类,包括4-羟基-L-脯氨酸、脯氨醇醚类等;重点阐述了固载L-脯氨酸类催化剂的载体类型和固载方法,催化剂载体类型主要包括离子液体、无机纳米粒子、有机聚合物以及新出现的聚合物离子液体和有机-无机杂化微球,固载方法主要包括硅烷化反应法、点击化学法以及可逆加成-断裂链转移(RAFT)聚合法,并对不同载体及固载方法的优缺点进行了总结。最后,针对目前固载化L-脯氨酸类催化剂存在的问题进行了原因分析并提出了改进建议,为以后新型固载化催化剂的研究开发提供了可能。 相似文献
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New efficient laccase immobilization strategy using ionic liquids for biocatalysis and microbial fuel cells applications 总被引:1,自引:0,他引:1 下载免费PDF全文
Said Galai Antonia Pérez de los Ríos Francisco José Hernández Fernández Issam Smaali 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2018,93(1):174-183
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Chao Xu Luca Deiana Samson Afewerki Celia Incerti‐Pradillos Oscar Crdova Peng Guo Armando Crdova Niklas Hedin 《Advanced Synthesis \u0026amp; Catalysis》2015,357(9):2150-2156
Porous organic polymers have prospects as functional substrates for catalysis, with quite different molecular properties from inorganic substrates. Here we disclose for the first time that porous palladium(II)‐polyimines are excellent catalysts for cooperatively catalyzed and enantioselective cascade reactions. In synergy with a chiral amine co‐catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all‐carbon quaternary stereocenter, were synthesized in high yields. High diastereo‐ and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations (DYKAT) of enals with propargylic nucleophiles.
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Nadiya Koukabi Eskandar Kolvari Mohammad Ali Zolfigol Ardeshir Khazaei Behzad Shirmardi Shaghasemi Behzad Fasahati 《Advanced Synthesis \u0026amp; Catalysis》2012,354(10):2001-2008
Surface functionalization of magnetic particles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. The introduction of magnetic particles (MPs) in a variety of solid matrices allows the combination of well‐known procedures for catalyst heterogenization with techniques for magnetic separation. We have conveniently loaded sulfonic acid groups on magnetic particles supports in which chlorosulfonic acid is used as sulfonating agent. The main targets are room temperature, solvent‐free conditions, rapid (immediately) and easy immobilization technique, and low cost precursors for the preparation of highly active and stable MPs with high densities of functional groups. The inorganic, magnetic, solid acid catalyst was characterized via Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer (VSM) and titration. The catalyst is active for the Hantzsch reaction and the products are isolated in high to excellent yields (90–98%). Supporting this acid catalyst on magnetic particles offers a simple and non‐energy‐intensive method for recovery and reuse of the catalyst by applying an external magnet. Isolated catalysts were reused for new rounds of reactions without significant loss of their catalytic activity. 相似文献
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Minghui Sun Chen Chen Lihua Chen Baolian Su 《Frontiers of Chemical Science and Engineering》2016,10(3):301-347
Great interests have arisen over the last decade in the development of hierarchically porous materials. The hierarchical structure enables materials to have maximum structural functions owing to enhanced accessibility and mass transport properties, leading to improved performances in various applications. Hierarchical porous materials are in high demand for applications in catalysis, adsorption, separation, energy and biochemistry. In the present review, recent advances in synthesis routes to hierarchically porous materials are reviewed together with their catalytic contributions. 相似文献
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Marko D Mihovilovic 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(12):1067-1071
The combination of biotransformations and metal‐assisted catalysis within hybrid systems represents a promising strategy to extend the repertoire of reactions enabled in a biomolecular environment. Both covalent catalytic entities and supramolecular assemblies have been created recently to mediate transformations otherwise difficult to perform in ‘classical’ biocatalysis. In this context, various biopolymers can serve as ligand spheres simultaneously acting as chiral inducers. In particular, modular approaches embedding novel metal‐based catalytic centers via an affinity interaction are highly appealing, as this technology may serve as a versatile platform to incorporate diverse reactivities in a biological matrix in a stereoselective fashion. Copyright © 2007 Society of Chemical Industry 相似文献
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以五元丙烯酸酯共聚物为改性剂,涤纶织物为载体,通过浸轧整理制备了负载型涤纶相转移催化织物,分析了催化织物在Williamson醚合成反应中的催化性能与反应机理,考察了整理工艺、改性剂结构、负载量对催化活性的影响。结果表明,磷酸与甘油可提升改性剂分子的交联程度,从而提高催化织物的稳定性;改性剂中长链烷基酯为甲基丙烯酸十八酯、阳离子单体为甲基丙烯酰胺丙基二甲基丁基溴化铵、阳离子单体摩尔用量为13.33%、负载量为20%时,织物催化活性最佳;催化织物可吸附油相于其表面,随后引发离子交换、成键反应;在应用于不同苯酚的Williamson醚合成反应时,产率均可达92%以上,催化织物在回用10次时仍具有较高的催化活性。 相似文献
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Chrétien Simons Ulf Hanefeld Isabel W. C. E. Arends Thomas Maschmeyer Roger A. Sheldon 《Topics in Catalysis》2006,40(1-4):35-44
The combination of immobilised Rh-MonoPhos (5-AlTUD-1) and Acylase I afforded a chemo-enzymatic one-pot process for the enantioselective synthesis of amino acids in water,
without the need for isolation of intermediates. In addition, the enzymatic hydrolysis increases the enantiopurity of the
product from 95% ee to >98% ee. Compatibility studies revealed that compartmentalisation of the catalysts is essential to
achieve high yields and optical purities. 相似文献